A light emitter having one or more light emitting devices such as laser diodes is known in the art. When the airtightness of a light emitter matters, a light emitter cover having a glass plate sealed to a frame via low melting glass is mounted to a case in which one or more light emitting devices are placed, for example.
With the advancement of technology, heat quantity generated by a light emitting device increases, which makes it necessary to bond the glass plate and the frame together more firmly than ever for a light emitter cover. For the purpose of firm bonding, there is a need to fill a gap, with low melting glass, between the peripheral side surface of a glass plate and the inner wall face of a frame so that the low melting glass wets the entire peripheral side surface of the glass plate.
For example, there is a method of filling a gap with low melting glass by applying low melting glass in paste form to the gap between the peripheral side surface of a glass plate and the inner sidewall of a frame, followed by curing the paste.
The method of applying low melting glass described above needs a large quantity of low melting glass in order to wet the entire peripheral side surface of a glass plate. As a result, the size of a light emitter cover increases, giving rise to the problem of an increase in the size of the light emitter. Reducing the quantity of low melting glass to facilitate size reduction results in a failure to wet the entire peripheral side surface of a glass plate with low melting glass. This causes the problem of a lowered sealing reliability between the glass plate and the frame.
[Related-Art Documents]
[Patent Document]
[Patent Document 1] Japanese Patent Application Publication No. 2006-156528